Surface state properties of clean cleaved silicon as derived from the temperature dependence of the surface photovoltage

The temperature dependence of the surface photovoltage of clean silicon surfaces cleaved in UHV was investigated with a special emphasize on that temperature where surface photovoltage changes its sign. The surface photovoltage was measured by the electron beam method. Chopped light with an energy larger than the bandgap of silicon was used. The ratio of the transition probabilities $\text{r}{}_{\mathrm{V}}\text{r}{}_{\mathrm{C}}$ for transitions from and into the surface states has been derived from the surface photovoltage and the value for the band bending at the clean silicon surface. It is concluded from model calculations that at temperatures below the sign change of the surface photovoltage the signal height of the surface photovoltage is essentially determined by the surface recombination whereas the contribution due to band bending is negligible.